Rubber covered copper article



July 1o, 1945. A. Wl MEYER 2,379,978

RUBBER COVERED COPPER ARTICLE Filed June 12, 1941 TTRNEY Patented July 10,1945

RUBBER COVERED COPPER ARTICLE Albert W. Meyer, Nutley, N. J., assignor to United States Rubberompany, New York, N. Y., a corporation oi' New Jersey Application June 12, 1941, Serial No. 397,820

7 Claims.

This invention relates to rubber covered copper articles, and more particularly latex-rubberinsulated electrical conductors having a metallic copper conducting core whereby to inhibit or prevent the discoloration of the rubber by the copper.

While the invention isnot limited to wire, it is particularly important in that eld. Rubber insulation on copper wire rapidly decreases in Itensile strength and other physical properties, and in the case of light colored` stock, the rubber insulation is soon darkened. The copper has a harmful eiect on rubber; it causes reduction in tensile strength, modulus, and abrasion resistance, and eventually may produce a sticky mass. Tinning of .the copper before the rubber covering is applied reduces the harmful effects but is not completely eective since the copper can migrate through the tin into the rubber. Also, the harmful effects of the copper on-the rubber may be decreased by incorporating in the rubber certain chemicals called copper xatives such as N,Ndi phenyl p-phenylene diamine, N,N'dinaphthyl p-phenylene diamine. disalicylal ethylene diamine, disalicylal diethylene triamine, reaction products of salicylaldehyde and polyethylene polyamine mixtures, salicylal triethylene tetramine, `sym-ethylene bis-amino isobutyrontrile, sym-ethylene bis-camino isobutyric acid, 8-hydroxy quinoline, and p-(p-toluene sulfonylamino)phenyltolylamine, etc. Even this known procedure does not give the desired protection against copper.

According to the present invention, the copper wire or tinned copper wire is coated with a synthetic resin composition containing the copper xative. 'I'he copper xative employed may be any of those known to the art such as those mentioned above. The rubber insulation is then applied over the resin coating. The accompanying drawing shows this relationship. The resin coating containing the flxative prevents deterioration of the rubber by posing as a barrier between the rubber and the copper.

The following example is given to illustrate the invention, the parts being by weight:

EXAMPLE I A #14 tinned copper wire was coated with a thin illm c! resin by passing it through a resin emulsion prepared as follows:

Dimethylamine oleate -..--a

This mixture was made up warm to assist in .the emulsiiication of the disalicylal'ethylene diamine.

Composition B Parts byweight Water 1866 Concentrated ammonia 19 Dimethylamine oleate 35 lRHoplex Resin WG9 3938 2 RHoplex Resin WD10 i 675 1 25% aqueous emulsion of 90% methy1-acry1ate-10% ethyl acrylate copolymer. A

25% aqueous emulsion of ethyl acrylate polymer. The resin emulsion, which is a mixture of Compositions A and B in the proportions indicated,

. and thus contains 0.5% of copper xative based on the weight of the resin solids, was put in the rst tank of a latex wire dipping machine. Tinned copper wire was passed` through the resin solution, was dried at an average temperature of 219 F., and was then repeatedly coated with latex and dried, until six latex dips had been applied. Then the coated wire was cured in saturated steam forv Percent reduction in coppermigration Grams copper in rubber/sq. in. Wire Grams copper/ Barrier coating grams rubber None Resin only 3) Resin disalicylal ethylene diamine.

Tensile strength tests were also made on these samples with the following results:

Tensl strength after 2 weeks in Geer oven Percent depreciation in tensile Percent de reciat on in tenslle Original tensil strength :sono

The samples after Geer aging also lshowed the eflect oi the resin, with or without the anti-copper conditions; similar wire which was coated withA the resin emulsion prevents the formation of black spots for 6 months, or more. After 11 months, the rubber insulation of resin-treated wire has a few black spots, but these are not very prominent and do not impair the appearance or usefulness of the wire; the rubber insulation of untreated wire is badly discolored by black spots.

Instead of resin emulsions, resin solutions in water or inorganic solvents, or molten resin, may u be used. Resins which have been useful in practicing the invention are; acrylic esters, methacrylic esters, methyl cellulose, phenol-modied alkyd, alkyd, heat-hardenable phenol-formaldehyde, urea-formaldehyde, alkyd-modifled ureaformaldehyde, polyvinylalcohol. The resin may be applied either by dipping, or by spraying, brushing, or any other convenient method.

The following table gives data on other resin coatings containing Example I copper fixative in the same concentrationas in Example I:

Gms. copper Percent Gms. co Resin coating per/100p llgfgte/f regjg gms' rubber wire migration None 0.154 1.848 Soft acrylic ester resin. .003 0. 042 98 Urea-formaldehyde (pla 1- cized) 011 0. 166 93 Polyvinylalcohol 003 0. 041 98 None v202 l. 670 Hard acrylic ester resn. 016 0.136 92 By the method described, it is possible to reduce the amount of anti-copper chemical required for the protection of a rubber-covered conductor. Thus, in Example I cited above .an extremely thin coating represented by .00071 lb. of disalicylal ethylene diamine per 1000 feet of wire was used, or .036% on the rubber for wire covered with 0.9 gm. rubber per ft. of wire, whereas for protection of the rubber against copper by incorporating the chemical in the rubber, .1 to 2% would be required, or 3 to 6 times as much 'as used in the present invention, and the degree of protection against copper is much less than by the present procedure.

Preferred resins are those which will preserve lm continuity at elevated temperatures, such as 220 F. and above.

The inhibition of copper migration by the resin vcoating depends on the resin molecule having low adsorptive attraction to copper and not reacting chemically to form an unstable molecular complex.

Plasticizers may be incorporated in the resin composition when necessary in order to give it a desired degree of ilexibility, since it is desirable that the resin coating be substantially continuous and flexible as would be needed by a copper wire.

Having thus described my invention, what I claim and desire to protect by Letters Patenty is:

l. A composite rubber-covered copper article in which a highly effective barrier consisting of a substantially continuous exible resin coating containing in addition to the resin an organic amine copper fixative is interposed between lthe rubber and the copper.

2. A rubber insulated electrical conductor having a metallic copper conducting core, which core carries a substantially continuous flexible resin coating containing in addition to the resin an organic amine copper xative as a highly effective shield between the conducting core and the rubber sheathing whereby to prevent discoloration of the rubber by the copper.

3. A latex-rubber insulated electrical conductor having a metallic copper conducting core, which core carries a substantially continuous flexible resin coating containing in addition to the resinA an organic amine copper'xative as a highly effective shield between the conducting core and the rubber sheathing whereby to prevent discoloration of the rubber by the copper.

4. A rubber insulated electrical conductor having a metallic copper'conducting core, which core carries a substantially continuous ilexible acrylic ester resin coating containing in addition to the resin an organic amine copper xative as a highly effective shield between the conducting core and the rubber sheathing whereby to prevent discoloration of the rubber by the copper.

5. A latex-rubber insulated electrical conductor having a metallic copper conducting core, which core carries a substantially continuous flexible resin coating containing disalicylal ethylene diamine as a shield between the conducting core and the rubber sheathing whereby to prevent discoloration of the rubber by the copper.

6. A rubber-insulated electrical conductor having a conducting core of copper, a covering of rubber composition of sucient thickness to provide an electricallyinsulating layer, and a highly eiective shield to prevent copper migration between the core and the rubber, said shield comprising a substantially continuous flexible resin layer containing an organic amine copper fixative, the resin lay'e'r being so thin as to have no substantial electrical insulating properties.

7. A rubber-insulated electrical conductor having a conducting core of copper, a covering of rubber composition of sufficient thickness to provide an electrically insulating layer, said covering being substantially identical with the dried-in-situ deposit of liquid rubber latex, and a highly effective shield to prevent copper migration between the core and the rubber, said shield comprising a substantially continuous flexible resin layer containing an organic amine copper fixative, the resin layer being so thin as to have no substantial electrical insulating properties.

ALBERT W. MEYER. 

